1. Field of the Invention
The present invention relates to devices for grinding surgical needles, and more particularly to devices, including grinding wheels, for abrading the needle to provide a surgical cutting edge on the needle through the use of an abrasive surface for grinding and/or polishing a needle, or a multiplicity of needles, simultaneously. The present invention additionally relates to an apparatus and a grinding wheel for producing hollow ground surgical needles.
2. Description of the Related Art
Surgical needle manufacture is a precise and time consuming procedure, particularly where individual needles are formed one at a time. Conventional surgical needle manufacturing typically begins with the step of cutting round wire stock to a predetermined length to form a needle blank. One end of the blank is then tapered to provide a point thereon. In some instances, such as for example in plastic surgery needles or taper cutting edge needles, a cutting edge must be formed at or near the point of the needle. To provide a cutting edge, the tapered end of the needle is stamped or pressed and then subjected to grinding and/or polishing to sharpen its longitudinal edges. Normally, at least a portion of the needle blank is pressed to provide flat surfaces on a portion of the needle to facilitate grinding. After the cutting edge is formed on the needle, the needle blank is cut to its final desired length and then prepared for suture attachment. The needle may be further subjected to additional steps such as polishing or hardening.
Conventional needle processing is in large part a manual operation. Providing a cutting edge, for example, typically includes the steps of: grasping and holding a needle using a hand held device; manually moving the needle into contact with a rotating abrasive belt or grinding wheel; visually evaluating and/or confirming the progress of needle cutting edge formation; and repeating the steps of manually contacting the needle with the abrasive surface and visually checking the progress of the cutting edge formation for each edge to be applied to the needle. Since visual confirmation of a specified cutting edge in the view of the person performing the operation is required, the reproducibility, accuracy and hence quality of the cutting edge is largely a function of the skill and experience of the operator.
More specifically, in the prior art the needle may be held by a pliers-like device or a chuck which grips an end of the needle opposite from the end of the needle where the cutting edge is to be applied. Usually, no more than two needles can be held in the device at one time, and the pliers-like device or chuck is used to manually engage the needle end with a rotating abrasive belt or wheel. The end of the needle is maintained in contact with the abrasive belt or wheel until the desired cutting edge is fashioned.
Grinding wheels used in previously known methods are typically of the bonded type and generally require frequent redressing. During use, the abrasive grains on bonded grinding wheels become slightly dulled. Normal stresses in the grinding operation tear the worn grain from the wheel to expose a new cutting grain. A soft wheel wears too fast, losing grains before they are dulled, whereas too hard a wheel develops a smooth glazed surface which does not cut properly. As the abrasive wears, the configuration of the wheel surface changes enough to affect the grind on the finished product. When this occurs the wheel must then be re-dressed to open new abrasive grain surfaces or to recondition the grinding surface. The re-dressing is performed manually and may vary from operator to operator. Even slight variances may cause needle geometries to depart from the strict specifications, thereby resulting in a higher percentage of rejected parts and concomitant higher costs.
Needle sharpness, both of its point and cutting edges, is an important factor during many surgical procedures. The surgeon's ability to perform delicate suturing operations is severely limited by needles with points and edges which are not sharp or which do not remain sharp. While flat pressing facilitates the formation of a needle edge, there is yet need of a way to increase and maintain the sharpness to which the cutting edge of a needle can be ground.
One disadvantage to conventional needle abrading devices is that manually positioning needles for abrading can be irregular and inefficient. Additionally, the engagement and extent of the needle processing is visually monitored which can result in an inconsistent needle cutting edge. Another disadvantage of the conventional methods is the reliance on visual affirmation of the needle cutting edge which can be ineffective for meeting precise surgical needle specifications. Finally, the prior art devices provide for substantially little or no automation so that the process is time consuming.
The novel device for applying a cutting edge to a surgical needle obviates the disadvantages encountered in the prior art and provides a device for automatically processing a plurality of needles at the same time. The device provides consistent and reproducible results, particularly with respect to needle geometry and surface finish, which ensures precision and accuracy in the application of cutting edges to needles during large scale manufacture. The device provides for both grinding the cutting edges onto the needle, as well as polishing and deburring to produce the finished product. The device also permits the application of cutting edges on several sides of the surgical needle without necessitating the removal and repositioning of the needles in the device to result in a precision multi-sided cutting edge surgical needle.